Many tissue products, such as facial tissue, bath tissue, paper towels, industrial wipers, and the like, are produced according to a wet laid process. Wet laid webs are made by depositing an aqueous suspension of pulp fibers onto a forming fabric and then removing water from the newly-formed web. Water is typically removed from the web by mechanically pressing water out of the web which is referred to as “wet-pressing”. Although wet-pressing is an effective dewatering process, during the process the tissue web is compressed causing a marked reduction in the caliper of the web and in the bulk of the web.
For most applications, however, it is desirable to provide the final product with as much bulk as possible without compromising other product attributes. Thus, those skilled in the art have devised various processes and techniques in order to increase the bulk of wet laid webs. For example, creping is often used to disrupt paper bonds and increase the bulk of tissue webs. During a creping process, a tissue web is adhered to a heated cylinder and then creped from the cylinder using a creping blade.
Another process used to increase web bulk is known as “rush transfer”. During a rush transfer process, a web is transferred from a first moving fabric to a second moving fabric in which the second fabric is moving at a slower speed than the first fabric. Rush transfer processes increase the bulk, caliper and softness of the tissue web.
As an alternative to wet-pressing processes, through-drying processes have developed in which web compression is avoided as much as possible in order to preserve and enhance the bulk of the web. These processes provide for supporting the web on a coarse mesh fabric while heated air is passed through the web to remove moisture and dry the web.
Additional improvements in the art, however, are still needed. In particular, a need currently exists for an improved process that reorients fibers in a tissue web for increasing the bulk and softness of the web without having to subject the web to a rush transfer process or to a creping process.